1. Field of the Invention
The present invention relates to a musical tone synthesizing apparatus used in, e.g., an electronic musical instrument.
2. Description of the Prior Art
In a conventional sound source system used in an electronic musical instrument, various musical tone synthesizing apparatuses or circuits controlled by, e.g., a microcomputer (to be referred to as a CPU hereinafter) are used. Typical systems can be roughly classified into:
(1) a system wherein all the musical tone control parameters are supplied from a CPU, in other words, a system wherein various musical tone parameters are mainly controlled by the CPU; and PA1 (2) a system wherein a CPU supplies only real-time performance instructions such as designation of pitches of musical tones, generation start and end timings of musical tones, and the like, parameters for determining characteristics of musical tones are stored in a parameter memory connected to a musical tone signal generator (sound source), and readout control of these parameters is performed by the sound source.
According to the system (1), musical tones are easy to control while performing various arithmetic processing operations of musical tone parameters by the CPU and software, and a musical tone generation system which can be used in various modes can be constituted. According to the system (2), a system depending on a performance of a CPU to be used can be constituted, and manufacturing cost can be reduced.
However, when the system (1) is employed, this system can be used in various modes, but poses problems that about synchronization between a sound source and the CPU, i.e., synchronization devices are necessary. As a result, manufacturing cost tends to be increased considerably. On the other hand, the system (2) has a problem that various musical tone parameters cannot be set in the system.